I never understood the paranoia about using the same container to mix dev/stop/fix as long as it's rinsed out between uses. The remote chance that a few molecules of "x" chemical may stick around leaves the contamination at parts per zillion, and so what? All the fuss about cross contamination only to wind up putting all of the chemicals into the same film development tank during use.

Just give it a good warm water rinse between mixing your chemicals and you'll be fine. Maybe a good wipe down with a disposable paper towel if you want to be extra cautious.